* {
  padding: 0;
  margin: 0;
  list-style: none;
}

.box {
  margin: 0 auto;
  width: 800px;
}
.box > .img-box {
  position: relative;
}
.box > .img-box > ul {
  position: relative;
  height: 250px;
  width: 100%;
}
.box > .img-box > ul > li {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
}
.box .img-box > ul > li > img {
  width: 800px;
  height: 300px;
}
.li-active {
  z-index: 10;
}

.arrow-left,
.arrow-right {
  width: 30px;
  height: 50px;
  background-color: rgba(0, 0, 0, 0.3);
  text-align: center;
  line-height: 50px;
  cursor: pointer;
}
.arrow-left {
  position: absolute;
  top: 50%;
  left: 0;
  transform: translateY(-50%);
  z-index: 2;
}

.arrow-right {
  position: absolute;
  top: 50%;
  right: 0;
  transform: translateY(-50%);
  z-index: 2;
}

.dot-box {
  text-align: center;
}
.dot-box > span {
  display: inline-block;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  margin: 0 10px;
  background-color: #fff;
  cursor: pointer;
  border: 1px solid #000;
  box-sizing: border-box;
}

.dot-box > span:hover {
  background-color: #000;
}

.dot-box .dot-active {
  background-color: #000;
}
